This isn't a trivial problem, it doesn't sound stupid. Hoarders are a big fat PITA and very difficult to live with, it is absolutely reasonable to have this awful habit as a dealbreaker.
I think you need to sit down with him and explain that you can't live like this and that he needs to get a new house to house all his crap.
Or he could build a shed in the garden for it.
Or start prioritising which of his crap is actually important to him.
I can be harsh about hoarders because I used to be one. It dawned on me that I have a limited amount of space and I need to prioritise what it's important for me to keep in that space. But before I got to that point, I had to do an awful lot of thinking and talking (to a counsellor) about a whole load of other shit in my life which was weighing me down like the crap I was hoarding. Once I'd done that, I could see the wood for the trees.
I'm not saying he needs counselling to stop this habit, but he might do and he might benefit from it.
Also, fuck it, you actually cry about this every day and he doesn't seem to care? He can fuck right off tbh. People who care about each other, try not to make each other cry at all, much less every day. They don't ignore the fact that they're making the other person unhappy.
I hope you manage to sort it out.